Laminates of films and methods and apparatus for the manufacture

ABSTRACT

A laminate of thermoplastic polymeric films comprises at least one fluted ply A and at least one substantially flat ply B, adhered to one another in bonded zones along the flute crests. The wavelength of the flutes is preferably no more than 3 mm. Ply A has a generally uniform thickness or can have attenuated zones of lessor thickness extending parallel to the flute direction, each bonded zone being located mainly within an attenuated zone. The flutes can be sinuous with crests on both sides of ply A and can be adhered on each side to a ply B, in which case, attenuated zones can be on both sides and can have different widths. The flutes can be filled with filler material, including reinforcement strands, and one or both sides can be perforated. The method and apparatus employ aligned grooved fluting rollers and a grooved laminating roller.

[0001] The present invention relates to a flexible laminate of filmsfrom thermoplastic polymer material for applications in which relativelyhigh yield strength and ultimate tensile strength is required, and amethod and apparatus for its manufacture.

[0002] Examples of such applications are: tarpaulins, pondliners,substitute of geotextiles, weather protective laminates, greenhousefilm, industrial bags, carrier bags and self-standing pouches.

[0003] For economical reasons there is an increasing need to reduce thethickness or square metre weight of flexible film made fromthermoplastic polymer material. The limits are partly set by therequired strength properties, and partly by the required self supportingcapability, i.e. stiffness with respect to banding. These needs havemainly been met by selected developments of the thermoplastic polymercompositions and as far as the strength is concerned also by biaxialorientation, or by cross-lamination of films each of which exhibits agenerally monaxial or unbalanced biaxial orientation.

[0004] From strength point of view essential savings can be achieved bysuch orientation and/or cross-lamination processes.

[0005] Thus as an example an industrial bag made from extrudedpolyethylene film of the best suited grades and destined for packing of25 kg polyethylene granules must generally have a thickness of 0.12-0.15mm in order to satisfy the normal strength requirements, while thisthickness can be brought down to about 0.07 mm by use of optimizedoriented and cross-laminated film from polyethylene. However, when thiscross-laminate is made in the known manner, few available types ofmachines for manufacturing bags from film, and few available types ofmachines for filling the bags, can work adequately with film which is sothin and flimsy.

[0006] A cross-laminate which, besides the improved strength propertiesobtained by the orientation and cross-lamination also by virtue of itsgeometrical structure shows significant improvements in this respect, isdescribed in the inventor's earlier Specification EP-A-0624126.

[0007] This is a cross-laminate of a slightly waved configuration inwhich the material of the curved crests on one or both sides of thelaminate is thicker than elsewhere, the material between these thickercurved crests being generally straightened out. (See FIGS. 1 and 2 ofsaid patent publications.) The structure is obtained by stretchingbetween several sets of grooved rollers under special conditions. Thisstretching also imparts transverse orientation. The disclosedwavelengths of the final products are between 2.2 and 3.1 mm.

[0008] Cross-laminates according to the said patent have been producedindustrially since 1995 for manufacture of industrial bags fromcombinations of high molecular weight high density polyethylene(HMWHDPE) and linear low density polyethylene (LLDPE) with film weightabout 90 gm⁻², and the slightly waved shape in combination with thethickened crests imparts a stiffness in one direction of the film whichhas proven to be very important for the performance of the bag machineswith such relatively thin film. However, the film is not adequate forwork with the 70 gm⁻² gauge which satisfies the strength requirements.

[0009] Furthermore the corrugated character of the film surface makes aparticularly fine print (as often required) impossible and also to someextent reduces the friction between filled bags in a stack, when thelayers of this stack are built up with the bags in crisscrossingarrangement as usually done.

[0010] As another example an agricultural tarpaulin (e.g. for protectionof crops) made from a 70 gm⁻² cross-laminate of oriented polyethylenefilms would be a fully adequate substitute of a 100 gm⁻² tarpaulin madefrom extrusion-coated woven tape, if only objective criteria wereapplied. However, in actual fact the average customer to agriculturaltarpaulins makes his choice to a great extent on the basis of the“handle” and the appearance, and will reject the 70 gm⁻² tarpaulin dueto its flimsiness, judging that it lacks substance.

[0011] The stiffness can of course always be increased by suitableincorporation of a filler, (and the present invention includes that asan additional option) but this will always more or less be at theexpense of puncture and tear propagation resistance, especially underimpact actions.

[0012] Object of the present invention is to add a “feel of substance”and improve stiffness in laminates of films at least in one direction,without sacrificing the laminate's character of feeling and looking likea generally two-dimensional structure, furthermore without essentiallyharming the puncture and tear propagation resistance, and when desiredalso providing a good printability at least on one side of the laminate.

[0013] The basic idea behind the present invention is to apply thecorrugated paperboard principle to laminates of thermoplastic films, butin such a way that the flute structure is made extraordinarily fine(“minifluted”), so as to obtain a laminate which, in spite of thestructurally increased stiffness (at least in one direction), can stillsatisfy the above-mentioned conditions.

[0014] In itself the application of the corrugated paperboard principleto the thermoplastic film is not new, but the finest flute structurewhich has been disclosed in patent literature, namely in U.S. Pat. No.4,132,581 col. 6, ln. 66, is 50±3 flutes per foot corresponding to awavelength of about 6.0 mm. It must also strongly be doubted that awavelength lower than this can be achieved by the method disclosed inthe said patent, in which the first bonding process takes place underuse of a row of many sealer bars supported and transported by a belt.

[0015] The sealer bars are transverse to the direction of movement (themachine direction) so the fluting also becomes perpendicular to thisdirection.

[0016] The use of the method of the said U.S. patent is stated to bemanufacture of board material, and the thickness of the fluted ply isindicated to be about 0.004-0.025 inches (0.10-0.625 mm). In the exampleit is 0.018 inches (0.45 mm). Other patents dealing with the use of thecorrugated paperboard principle to thermoplastic film for the making ofpanels or boards are U.S. Pat. No. 3,682,736, U.S. Pat. No. 3,833,440,U.S. Pat. No. 3,837,973, EP-A-0325780 and WO-A-94/05498.

[0017] Japanese Patent Application Hei 02-052732 discloses laminatesconsisting of a corrugated thermoplastic film bonded to a flatthermoplastic film, which on its other side is bonded to paper. (Thepaper and flat sheet are first joined and then the corrugated film isadded.) The flutes, which also in this case are perpendicular to themachine direction are pressed flat and adhesively closed at intervals sothat a large number of airtight vesicles are formed. The stated use ofthis product is for cushion material, sound insulating material, heat-and moisture-insulating material and wall decorative material. Thethickness of the corrugated sheet and flat sheet are not indicated,neither are the wavelength of the fluting and the length of thevesicles, but it is mentioned that the dimensions can be selecteddepending on the use of the laminate. However, it must be understood asimplied that the wavelength in any case will be no lower than the lowestmentioned in the above-mentioned U.S. Pat. No. 4132581 (i.e. about 6mm). One reason for judging this is that this would not be advantageousfor the mentioned purposes, except for decoration, while another reasonis that the disclosed apparatus would not be able to work with a lowerwavelength (i.e. a lower pitch of the gear rollers) except for making anextremely shallow and practically useless fluting. This is due to thefact that thermoplastic film is resilient and not permanently formableat ambient temperature which as implied by the presentation in thedrawing is used in the said method. If the pitch is low on the gearrollers which produce the fluting and the lamination, the corrugatedfilm will “jump out” of the grooves in the forming and laminating rollerduring its passage from the location where forming of flutes takes placeto the location where bonding takes place. The patent publication doesnot mention any means to hold the flutes in shape in the grooves of theroller.

[0018] In a conventional corrugator for manufacture of corrugatedpaperboard there are provided tracks or shield to hold the fluted paperin the grooves. At ambient temperature this allows the paper to be morereadily permanently formed.

[0019] Similar tracks or shields in unmodified form cannot be used withthermoplastic film under production conditions since friction againstthe track or shield quickly would create congestion by heating of thepolymer.

[0020] An improved, frictionless way of holding of flutes of paper inthe grooves of a roller is known from U.S. Pat. No. 6,139,938, namely bymaintaining a controlled under pressure within the grooves (see FIGS. 9and 10 and col. 7 lines 25-34). This U.S. patent deals entirely withcorrugated paper laminates having particularly low wavelength whilemanufacture of corrugated structures from thermoplastic films is notmentioned. However, the improved method of holding the flutes will infact also, depending on the film thickness, be applicable to fine flutesin thermoplastic film. This was found in connection with the developmentof the present invention. However as mentioned above, the Japanesepatent application does not disclose any precautions to hold the flutesin shape in the grooves.

[0021] The development of the particularly fine flute structure, the“miniflutes”, which is the object of the present invention has made thecorrugated paperboard principle applicable to completely differentfields of use such as the fields mentioned at the very beginning of thisspecification.

[0022] This has comprised a development of new types of machinery basedon grooved rollers with a very fine pitch. As it will appear from theexample the wavelength in a 90 gm⁻² “minifluted” 2-ply laminate (eachply about 45 gm⁻²) has in actual fact been brought down to 1.0 mmthrough a process which can be carried out industrially, and aftershrinkage of the flat ply transversely to the flutes it has even beenbrought down to 0.8 mm. Especially by further use of shrinkage it canprobably be brought further down e.g. to about 0.5 mm. The mentioned2×45 gm⁻² corresponds to an average thickness of about 0.074 mm (2×0.037mm) if the laminate were pressed flat.

[0023] The invention is not limited to pressed-flat thicknesses aroundthis value, but also comprises, very generally speaking, miniflutedlaminates of an average thickness in compacted form which is roughlyabout 0.3 mm or lower. Thicknesses down to 0.03 mm or even lower can bemade for special purposes.

[0024] Nor is the invention limited to the use in connection withcross-laminates of oriented films. For different purposes differentcombinations of strength properties are required. Cross-laminates can,as is known, be produced with suitable combinations of severalcategories of strength properties but for many purposes other types ofstrength laminates may be preferable when the cost of the manufacturingprocess also is considered, and the present invention can also be usefulin such other strength laminates as it further shall be specified below.

[0025] By making the wavelength as low as 3 mm or less, the laminateloses its character of being a board material and gets appearance,handle and bending properties like a flexible film (see the example). Italso gets improved puncture properties, compared to laminates made fromsimilar plies but with longer wavelength, since in the latter there is alarge tendency for the plies to be ruptured individually instead ofcooperating in the resistance against the puncture.

[0026] The “minifluted” laminate also has the advantage that it canreceive a fine print on the flat side and a coarse print on thecorrugated side.

[0027] Compared to non-corrugated laminates of the same composition andsame square metre weight it feels much more substantial due to theincreased stiffness in one direction and due to the increased-volume.

[0028] In the case of cross-laminates it is well-known that a weakbonding between the plies, or strong bonding or line-bonding, gives muchimproved tear propagation resistance, since it allows the tear toproceed in different directions in the different plies. Thereby thenotch effect is reduced. Since a cross-laminate with one ply corrugatedwill be line-bonded, it will show improved tear propagation resistance,no matter whether the wavelength is short or long, however“mini-fluting” makes the tear stop after a very short propagation, whichof course is very advantageous in most cases.

[0029] For the sake of good order, it should be mentioned that therealready have been described “minifluted” laminates in literature,however laminates of which at least the fluted ply consists of amaterial which is not a thermoplastic film or an assembly ofthermoplastic films.

[0030] Thus U.S. Pat. No. 6,139,938, which has been mentioned above, hasfor its object a 3-ply paper laminate with a corrugated paper sheet inthe middle and flat paper sheets on each side, like normal corrugatedpaper board, however claimed to comprise 500-600 flutes per metrecorresponding to a wavelength of 1.67-2.00 mm. This state purpose is toimprove the printability.

[0031] Japanese patent publication No. 07-251004 relates to an absorbingproduct in which a plane thermoplastic synthetic fiber sheet isthermally bonded to a corrugated sheet mainly consisting of activecarbon fibers. The wavelength of the corrugation is 2.5-20 mm.

[0032] Japanese patent publication No. 08-299385 relates to an absorbentlaminate consisting of a fluted non-woven fabric bonded on one side to aplane sheet or film, which can be a thermoplastic film. Between thesetwo plies there is nested a water-absorbing material. The wavelength isclaimed to be 3-50 mm, and it is stated that there would not besufficient space for the absorbing material if it were less. The productis for diapers and the similar products.

[0033] More precisely expressed the present invention concerns alaminate comprising at least a monofilm-formed or multifilm-formed ply(A) and another monofilm-formed or multifilm-form ply (B) both mainlyconsisting of thermoplastic polymer material, whereby at least Aconsists of cold-orientable material in which A has a waved fluteconfiguration while B is not waved, and B on a first side is adhesivelybonded in bonding zones to the crests on a first side of A. Acharacterising feature of the laminate is that the wavelength of thesaid configuration is no more than 3 mm. The use of cold-orientablematerial in A is important for the strength of the product. Furthermoreit is normally important that the adhesive bonding has been establishedthrough a lamination layer, so that melting of the main portions of Aand B can be avoided during the lamination process, and that either thethickness of A generally is the same within the non-bonded zones as itis within the bonded zones, or A exhibits zones which are attenuated inthe solid state and extend parallel to the flute direction in such amanner that each bonding zone mainly is located within one of theattenuated zones. These attenuated zones will be referred to as the“first attenuated zones” since there also may be further attenuatedzones, as it shall be explained later.

[0034] In this connection, an essential attenuation of A in thenon-bonded zones, as compared to the thickness of A in the bonded zones,will of course have a negative-influence on the resistance to bending inthe stiff direction (but it is generally easier to make the flutedlaminate so). By contrast this resistance to bending is enhanced, seenin relation to the average thickness of ply A, when each bonding zonemainly falls within one of these attenuated zones. The attenuated zonesalso facilitate the manufacturing process as it later shall beexplained. It is noted that while attenuation by stretching in themolten state reduces the tensile strength, attenuation by stretching insolid state increases the tensile strength in the direction in whichthis stretching has taken place.

[0035] While I here have identified the laminate as comprising the pliesA and B, each “ply” can consist of one or more “films”, normallyextruded films, and each extruded film can and normally will consist ofseveral co-extruded “layers”. Thus the “lamination layer” through whichthe bonding takes place will normally be a co-extruded layer, however itcan also be a thin film applied in a conventional extrusion-laminationprocess.

[0036] While an upper limit of 3 mm wavelength has been chosen as asuitable value for distinguishing the product of the invention fromcorrugated board material, it is generally better to keep the wavelengthwithin 2.5 mm, preferably within 2 mm and more preferably 1.5 mm. Asalready mentioned and shown in the example the inventor has been able tomake it 1.0 mm and under use of shrinkage after lamination even 0.8 mm.

[0037] As it appears from the introduction, the use of the presentinvention is mainly for strength film. This needs not always mean goodstrength in all directions; by contrast there are cases, e.g. inconstruction of bags, where the focus should be on the strength in onedirection, combined with a certain puncture and tear-propagationresistance. As an example a conventional industrial bag of filmthickness 0.160 mm made from a blend of 90% LDPE and 10% LLDPE willtypically in its longitudinal direction show a yield force of 20 Ncm⁻¹,i.e. a yield tension of 12.5 MPa and in its transverse direction shows ayield force of 16 Ncm⁻¹, i.e. a yield tension of 10.0 MPa.

[0038] Cross-laminated film material in average thickness 0.086 mm forheat-sealable bags developed by the inventor and manufactured inaccordance with the above-mentioned EP-A-0624126 shows in its strongestdirection a yield force of 20 Ncm⁻¹, i.e. 23 MPa, and in its weakestdirection a yield force of 17 Ncm⁻¹, i.e. a yield tension of 20 MPa.

[0039] Since the invention in principle relates to flexible laminatesfor uses where relatively high strength is required, although theemphasis of the invention is on stiffness, feel and appearance, theyield tension of the laminate in its strongest direction should normallybe no less than 15 MPa, preferably no less than 25 MPa. Correspondinglythe ultimate tensile tension is conveniently about twice the saidindicated values, or more. Here the cross section in mm² is based on thesolid material only, not including the air spaces, and it is an average,considering that ply A may have attenuated zones.

[0040] The yield tensions mentioned here refer to tensile testing at anextension velocity of 500% per minute. They are established fromstrain/stress graphs. These graphs will begin linear accordingly toHook's law, but will normally soon deviate from linearity although thedeformation still is elastic. In principle the yield tension should bethe tension at which the deformation becomes permanent, but thiscritical value, which is velocity dependent, is practically impossibleto determine. The way yield tension normally is determined in practice,and also considered determined in connection with the present invention,is the following:

[0041] In case the tension reaches a relative maximum, then remainsconstant or decreases under continued elongation, later to increaseagain until break occurs, the relative maximum of the tension isconsidered to be the yield tension. The sample may also break at thispoint, and then the yield tension equals the ultimate tensile tension.If however the tension continues to increase with the continuedelongation, but with much lower increases in tension per percentageelongation, then the strain/stress curve after yield, and after itpractically has become a straight line, is extrapolated backward tointersect with the line which represents the Hook's-Law-part of thestretching. The tension at the intersection between the two lines is thedefined yield tension.

[0042] An embodiment of the invention is characterised in that the ply Aby the choice of polymer material or by an incorporated filler or byorientation, within the non-bonded zones exhibits an average yieldtension parallel to the direction of fluting, which when it isdetermined as explained above, is no less than 30 Nmm⁻² (cross-sectionof ply A alone), preferably no less than 50 Nmm⁻² and still morepreferably no less than 75 Nmm⁻².

[0043] As already mentioned, A is preferably solid-state-attenuated inzones (the “first attenuated zones”) and each bonding zone is mainlylocated within a first attenuated zone. These zones should be understoodas delimited by the positions where the thickness of A is an averagebetween A's lowest thickness within the first attenuated zone and A'shighest thickness within the adjacent non-bonded zone.

[0044] Another important embodiment of the invention is characterised inthat A within each non-bonded zone and outside the first attenuated zoneif such zone is present (delimited as mentioned above) is molecularlyoriented mainly in a direction parallel to the direction of the flutesor a direction close to the latter as established by shrinkage tests.Such tests are commonly used. In this connection, a component oforientation in A perpendicular to the direction of the flutes will notcontribute to the yield tension in any direction, but will contribute tocertain other strength properties.

[0045] A preferable limitation of the extension of each first attenuatedzone—preferable with a view to the stiffness in one direction—isspecified in claim 12, and preferable thicknesses of these zones arespecified in claim 21.

[0046] Additionally to the first attenuated zones it can be veryadvantageous to have a second solid-state-attenuated zone (hereinafterthe second attenuated zone) between each pair of adjacent firstattenuated zones. These second attenuated zones should be narrower thanthe first ones—preferably as narrow as possible but also alternated sothat the thickness of A in the zone is as thin as possible—and locatedon the crests of A on the side opposite to the bonded zones. They act as“hinges”, and if they are made narrow and deep enough they improve thestiffness since the cross-section of A becomes zig-zagging instead ofsmoothly waved (as described further in connection with FIG. 3) and Aand B thereby form triangular structures. They also essentiallyfacilitate the manufacturing process, which is explained below.

[0047] In addition to the improvements in stiffness caused by the firstand second attenuated zones (improvements seen in relation to theaverage thickness of A) each set of zones also normally improves theresistance against shock actions, i.e. they normally improve impactstrength, shock-puncture resistance and shock-tear-propagationresistance. This is because there is started a stretching (or furtherstretching if A already was stretched) and this stretching normally hasa tendency to progress under shock actions, whereby the first and secondattenuated zones can act as shock-absorbers.

[0048] Normally the wavelength of each flute including an adjacentbonding zone should be no longer than 50 times the highest thickness ofA within the flute, preferably no more than 40 times and still morepreferably no more than 30 times the said thickness. As an example, ifthe highest thickness of A is 0.037 mm as in the operative examplebelow, the mentioned values correspond to wavelengths of 1.85, 1.48 and1.11 mm respectively.

[0049] In order to “integrate” the plies conveniently with each other inorder for strength purposes, the width of each bonding zone shouldnormally be no less than 15%, preferably no less that 20% and still morepreferably no less than 309 of the wavelength, and in order to achieve asubstantial effect of the fluting, the width of each non-bonded zone ofA as measured between the two adjacent bonding zones and measured alongits curved surface, should preferably be no less than 10% and preferablyno less than 20% longer than the corresponding linear distance. This isa measure of the depth of the flutes.

[0050] For many purposes, e.g. when increased stiffness against bendingin all directions is wanted, there can be a non-waved monolayered ormultilayered film C on the side of A which is opposite to B as specifiedin claim 15.

[0051] A fluted outside surface on a bag has as mentioned above adisadvantage, namely in connection with printing and stacking of thefilled bag. However there are articles in which the special roughness ofa fluted surface can be very advantageous in use e.g. on mats. For sucharticles there can advantageously be two waved mono- or multilayeredplies (A) and (D) laminated to the two opposing sides of the non-wavedmono- or multilayered film (B), as specified in claim 16.

[0052] The films A, B, C and D will normally consist of polyolefin andwill normally be produced by a process which involves extrusion. Thiswill normally be a co-extrusion process by which lamination layers andoptionally heat-seal layers are joined with the main body of the film.

[0053] At least some of the flutes can be flattened at longitudinallyspaced intervals and preferably bonded across the entire width of eachflute at the flattened locations to make the flutes form a row of narrowclosed elongated pockets. Preferably the flattened portions of a numberof mutually adjacent flutes or of all flutes form a series of linestransverse to the longitudinal direction of the flutes. This can makethe corrugated laminate look and feel more textile-like, almost make theimpression of a woven structure, and make it more flexible in thedirection which otherwise is stiff, without losing the feel of bulk andsubstance. Flattening can also be used to create preferential locationsfor bending.

[0054] Further description of different embodiments of the product andof particular uses will follow after the description of the method.

[0055] In accordance which the above characterization of the laminate ofthe invention, the method of manufacture which takes place under use ofa grooved roller for formation of the flutes, and also under use of agrooved roller for the lamination by heat and pressure (which in certaincases can be the same grooved roller) is characterised in that thedivision on the roller which produces the lamination is at the highest 3mm. The new method according to the invention is as defined in claim 36.New apparatus suitable for carrying out the method is defined in claim65.

[0056] The apparatus can be adapted either to make the flutes generallyperpendicular to the machine direction as in conventional manufacture ofcorrugated laminates, or generally parallel to the machine direction.This will be specified below.

[0057] Normally the bonding is established through a lamination layer(produced by co-extrusion or by an extrusion lamination technique) inorder to avoid weakening, and normally the steps of the process areadapted either to avoid any significant attenuation of the zones in A,or alternatively a stretching in solid state between a set of groovedrollers is adapted to produce the above-mentioned “first attenuatedzones”, whereby the grooved roller for lamination is coordinated withthe set of grooved rollers for stretching in such a way that each zoneof bonding mainly becomes located within a first attenuated zone.

[0058] The “second attenuated zones”, which have been described above inthe description of the product, can be formed by stretching between afurther set of grooved rollers suitably coordinated with the groovedrollers which produce the first attenuated zones.

[0059] The advantages of the first and second attenuated zones in termsof product properties have already been explained. For the carrying outof the method, the first attenuated lines allow increases of velocityand therefore improved economy, since the zones in ply A which are goingto be bonded, have been made thinner and therefore require less heatingtime during the application of heat prior to the bonding. Furthermorethe first attenuated zones and in particular the combination of firstand second attenuated zones can be of great help for the process byacting as “hinges” in ply A. In the type of apparatus in which thegrooved roller for lamination has grooves which are generally parallelwith its axis, these “hinges” make it possible to direct even relativelyheavy A-ply into fine grooves. In the type of apparatus in which thegrooves are circular or helical, but in any case approximatelyperpendicular to the roller axis, the “hinges” help to keep ply A “intrack” during its passage from grooved roller to grooved roller, inother works the “hinges” help to coordinate the action of the groovedlamination roller with the action of the preceding set or sets ofgrooved rollers which form the flute under a simultaneous transversestretching.

[0060] While it is essential for normal uses of the invention forapplications as a flexible film that the division on the grooved rollerwhich produces the lamination on the crests is no more than 3 mm, it isgenerally recommendable to make it no more than 2.5 mm, preferably nomore than 2.0 mm and still more preferably no more than 1.5 mm.

[0061] The film or films used for ply A is preferably, prior to formingof the waved configuration and prior to making of the first and secondattenuated zones (if such zones are made), supplied with orientation inone or both directions, the resultant main direction of orientationbeing in the direction which is selected to become the direction offluting. This can be by means of a strong melt orientation, orpreferably, alternatively or additionally by known stretching procedurescarried out in the solid state. If the process is adapted to make theflutes generally parallel with the machine direction, this will be agenerally longitudinal orientation process, which is simple, and if theprocess is adapted to make the flutes generally perpendicular to themachine direction, it will be a generally transverse orientation processwhich is much more complicated to establish and usually requiresexpensive machinery. It is noted that neither of the two closestreferences, i.e. U.S. Pat. No. 4,132,581 and Japanese patent applicationHei 02-052732 have disclosures which indicate that ply A could beoriented in a direction generally parallel with the flutes. In these twopublications the flutes are formed in the transverse direction, and hadthere been thought of using transversely oriented film it would havebeen natural to mention this, since without special steps the film isnot formed so in the extrusion or casting process.

[0062] As it already has been described in connection with the product,a further non-waved monofilm formed or multifilm formed ply (C) ofthermoplastic polymer material can simultaneously with or subsequent tothe bonding of B to A be adhesively bonded to the crests of A on thesecond side of A. Another useful possibility is that, in a mannersimilar to the forming and application of A, there is produced a secondmonofilm formed or multifilm formed ply (D) having waved fluteconfiguration with a wavelength of preferably no more than 3 mm, and thecrests on one side of D are laminated to the second side of Bsimultaneously with or following the lamination of B with A.

[0063] In most applications of the invention the mono- or multifilmformed plies should mainly consist of polyolefin, and should be producedby a process involving extrusion. Furthermore the films constituting theplies should normally be made by co-extrusion in which there isco-extruded surface layers to enable the lamination without any meltingof the main body of the films.

[0064] As it also appears from the description of the product, some ofthe flutes at least can be flattened after the lamination. This is doneat intervals, preferably under heat and pressure sufficient to bond allfilms in the laminate to each other so that the flutes with adjacentfilm material form fine elongated pockets closed at each end. Theflattening can be carried out with bars or cogs which have theirlongitudinal direction arranged transversely to the flute directionand-which each covers a number of flutes, optionally the entire width ofthe laminate.

[0065] A suitably distinct formation of the first attenuated zones canbe established at least in part by giving the crests on the groovedstretching roller intended to produce the stripes a temperature which ishigher than the temperature of the crests on the other groovedstretching roller and/or by giving the crests on the grooved stretchingroller intended to produce the stripes a radius of curvature which issmaller than the radius of curvature of the crests on the matchinggrooved stretching roller. A significant orientation mainly in thedirection nearly parallel with the fluting, and/or a high co-efficientof elasticity (B) of ply A are also efficient means to give the firstattenuated zones suitably distinct borders.

[0066] A good way to make the fluting finer than this can be done bypurely mechanical means is by use of shrinkage. Prior to the laminationply B is supplied with orientation generally perpendicular to thedirection which becomes direction of fluting, and after the lamination Bis subjected to shrinkage in a direction generally perpendicular to thedirection of fluting.

[0067] As it already has been stated the waved flute structure can beformed in different directions. Thus it can be established mainly in A'slongitudinal direction under a generally transverse orientation processby taking A through a set of driven mutually intermeshing groovedrollers, the grooves of the rollers being circular or being helical andforming an angle of at least 60° with the roller axis. It is mostpractical to make this angle about 90° or at least very close to this.This can be arranged so that A moves directly from its exit from one ofthe grooved stretching rollers which form the waving on A to the groovedlamination roller, whereby these two grooved rollers are in closeproximity to each other and have the same pitch, and are mutuallyadjusted in the axial direction. The pitch, in this aspect should bemeasured at the operational temperature of the respective roller.

[0068] Alternatively A can move from this exit from one of the groovedstretching rollers which form the waving on A to the grooved laminationroller over one or a series of heated, grooved transfer rollers. Thegrooved rollers in this row start with the grooved stretching rollersand end with the grooved lamination roller and each is in closeproximity to its neighbour or neighbours. Each of the grooved rollers inthe row-has the same pitch (measured at the operational temperature ofthe respective roller) and their axial positions are adjustable to eachother (see FIGS. 7 and 8 and the example).

[0069] When the fluting is produced in the longitudinal direction bymeans of rollers with circular grooves, ply A's width measured as thedirect, linear distance will remain constant from its inlet to theprocess of the lamination, apart from deviations in very narrow edgeregions, which should be trimmed off. Therefore, the ratio between plyA's real width, measured along its curved extension, and A's linearwidth, which is the same as B's width, equals the transverse stretchratio and is related to the thickness reductions in the attenuatedzones.

[0070] However, as it already has been mentioned, the flutes can also beproduced in a distinctly transverse direction. In this embodiment, anangle of about 30° between the grooves and the roller axis is probablyabout the maximum which is practically possible, but it is simplest towork with grooves which are parallel with the roller axis.

[0071] The embodiment with grooves parallel to the roller axis isfurther defined in claims 56, 57, 58 and 59. The means to hold A influted form in the grooves from flute formation to bonding, and adaptedto avoid a frictional rubbing on A, can be devices for suction throughchannels from the inside of the grooved roller—a method which as alreadymentioned is known from making of corrugated paperboard—or it can be useof tracks or shields which are adapted from the constructions used inmanufacture or corrugated paperboard by being air-lubricated. This meansthat the tracks or shields are supplied with fine channels, orpreferably a part of each track or shield is made from porous, sinteredmetal, and pressurized air is blown through the channels or pores toform an air-film on which the fluted ply can flow.

[0072] The means for fine regulation mentioned in claims 58 and 59 aresimilar to registration means in multicolour printing technology.

[0073] The following sections will describe different selections of theorientation and/or elasticity in the different plies, specialutilization of the channels or pockets formed by the flutes, andparticular end uses of the product of the invention.

[0074] It has already been mentioned that, in an important embodiment ofthe product according to the invention, ply A within each non-bondedzone and outside the first attenuated zone if such zone is present, ismolecularly oriented mainly in a direction parallel to the direction ofthe flutes or a direction close to the latter.

[0075] With ply A so oriented, there are different preferable optionsfor ply B, depending on the uses of the laminate. One very importantoption is that B also is molecularly oriented and B's orientation withineach non-bonded zone in a direction perpendicular to the direction ofthe flutes is higher than A's average orientation in the same directionwithin the non-bonded zone. The said two components of orientation arealso in this case, indicated by shrinkage tests.

[0076] This does not necessarily mean that ply B must have its strongestcomponent of orientation in the transverse direction, in other words thelaminate needs not necessarily be a cross-laminate. Thus, ply B maysimply be a highly blown film, which by means of the high blow ratio hasobtained a relatively high transverse melt orientation. The embodimentis further specified in claim 8.

[0077] As mentioned there are cases, e.g. in bag construction, in whichthere is a need for a high yield tension in one direction only, butcombined with high puncture resistance. The laminate according to claim9 or claim 10 is designed for this.

[0078] As it appears from the foregoing the present invention is veryuseful in connection with cross-laminates, i.e. the laminate thencomprises at least two films each of which has a main direction oforientation and which are laminated so that the said two directionscross each other. Different ways of carrying out this aspect of theinventions appears from product claims 22 to 25, from which also themethod of making becomes clear.

[0079] Suitable methods and apparatus for cross-lamination may beachieved by combining the information in the above mentionedEP-A-0624126, mainly in its introduction, with the formation in theinventor's older GB-A-1526722. Thus, with reference to FIG. 4 of thepresent drawings, B and C may each be films, including laminates, whichexhibit a main direction of orientation whereby B's main direction oforientation criss-crosses with C's main direction of orientation. One ofthese directions may be parallel with the machine direction, the otherperpendicular thereto, or both may from an angle higher than 0° andlower than 90°, preferably between 20° and 70° and more preferably inthe range 25°-65° with the machine direction. In this arrangement thewaved A supplies to the laminate stiffness against bending, but at thesame time, since it establishes a “dislocated” bonding between B and C,it also has importance for the tear propagation resistance. It is knowne.g. from the above-mentioned GB-A-1526722, that the superior tearpropagation resistance which can be obtained by cross-lamination,depends on having bonding strength which is not too high, since the tearmust be allowed to develop along different directions in the differentplies of the cross-laminate. Since on the other hand the cross-laminateshould not be prone to accidental delamination during use, as forinstance described in the said patent, there can be used a combinationof strong bonding in spots or lines and a weak bonding over the rest.However, the “dislocated” bonding of cross-laminated B and C through thewaved A can provide a better combination of high tear propagationresistance and adequate bonding strength, especially when thecoefficient of elasticity E of film A is lower than the coefficient Efor both B and C, preferably by a factor of at least 1.5 and morepreferably at least 2. Furthermore the flutes may be flattened atintervals and bonded across each ones entire width to make the flutefrom a row of narrow, closed pockets. The purposes of such flatteninghave been mentioned above.

[0080] In the above description there is mentioned the “main directionof orientation” in the films B and C. If plies B and C each aremono-films, normally with coextruded surface layers, this may be amonoaxial or unbalanced biaxial orientation. However, each of the filmsB and C may also in themselves be cross-laminates, normally 2-plycross-laminates.

[0081] To clarify this, B may e.g. consist of two plies of equalcomposition, equal thickness and equal degree of orientation, but oneoriented at +30° and the other at −30° to the machine direction. Thiswill result in a main direction of orientation following the machinedirection. Similarly C may consist of two equal plies, one oriented at+60° and the other at −60°. The resultant direction of orientation thenis perpendicular to the machine direction.

[0082] Uniaxial or unbalanced orientation in a film can be obtainedunder use of spiral cutting of a tubular film with mainly longitudinaldirection as disclosed in EP-A-0624126 and GB-A-1526722, both mentionedabove, and disclosed in more detail in EP-A-0426702. The latter alsodiscloses a method of obtaining a uniaxial or strongly unbalancedmelt-orientation which is perpendicular to the machine direction, namelyby twisting of a tubular film coming out of the extrusion die followedby helical cutting under the calculated angle. Another embodiment of thecross-lamination aspect of the present invention is stated in claim 22.The expression “resultant main direction of orientation” has the samemeaning as explained above.

[0083] If this laminate is to be used in the construction of bags withheat-seals generally perpendicular to the direction of the flutes, andif such heat-seals may be subjected to high shock-peel forces then thelaminate should preferably be constructed as stated in claim 61. Thefluted softer A-film can then form the inner side for heat-sealing, andthe stiffer, smooth B-film can form the outer side of the bag.

[0084] Another aspect of the invention (“the encapsulation/canalizationaspect”) comprises a number of embodiments which for different practicalpurposes utilize the interior cavities in the laminate, optionally incombination with suitable perforations, either to canalize a flow ofliquid or air, or to encapsulate filling material in particulate,fibrous, filament or liquid form. The latter may e.g. be a preservativefor goods packed in the flexible laminate. These different embodimentsappear from product claims 27 to 30, 34 and 35. The method of makingthese products will appear from claims 48 to 51, and apparatus suitablefor carrying out the method is defined in claims 88 and 89.

[0085] The embodiment of the present invention in which the fine canalsor “pockets” are used to “bury” preservatives, have obvious advantagesover the usual method of blending such agents with the polymers to beextruded into film form. One advantage is that the concentration of thepreservative can be much higher, another that the preservative needs notbe able to withstand the temperature of extrusion. The preservative mayreach the object to be preserved by migration alone, or if the agent issolid it may gradually evaporate and diffuse through sufficiently fineperforations or pores.

[0086] It is also customary to contain preservative agents in small bagswhich are placed inside a package. Compared to this method ofprotection, the present invention has the advantage that thepreservative agent can be distributed almost homogeneously over the fullarea of the packing material.

[0087] The filter material stated in claim 30 has many potential uses,e.g. as a geotextile (claims 34 and 35) but also for instance for watertreatment in the chemical industry and in gas face masks.

[0088] Although the claims relating to these filter materials, includingthe weather-protective laminate of claim 62, formally depend on claim 1,it should be understood that similar products having wavelength somewhathigher than 3 mm also have important uses and are considered inventivenew products. Thus in a further aspect of the invention there isprovided a laminate comprising at least a monofilm formed or multifilmformed ply (A) and another monofilm formed or multifilm formed ply (B)both mainly consisting of thermoplastic polymer material, whereby atleast A consists of cold-orientable material in which A has a wavedflute configuration while B is not waved, and B on a first side isadhesively bonded in bonding zones to the crests on a first side of A inwhich the adhesive bonding has been established through a laminationlayer, and that either the thickness of A is generally the same withinthe non-bonded zones as it is within the bonded zones, or A exhibitsfirst solid-state-attenuated zones (hereinafter the first attenuatedzones) extending parallel to the flute direction, each bonding zonemainly being located within a first attenuated zone, the laminate beingmoisture resistant but air permeable. The laminates are useful forforming raincoats and tarpaulins. Other uses in which an additive isincorporated into the flutes are described below.

[0089] Other important uses of the invention are for bags andself-standing pouches. In this connection reference is made to theproduct claims 31, 32 and 33.

[0090] For all uses of the present invention, a very interesting andwear-resistant print can be obtained when, prior to the lamination, Aand/or B is supplied with print on the surface to become the inside ofthe laminate, the printing process being in register with theflute-forming and lamination processes so as to limit the printgenerally to the non-bonded zones. This durable print may form a text, adecorative pattern or simply lines which accentuate the fluting or thetextile-like appearance of the laminate. Special decorative effects canbe achieved if the print provides a metallic appearance or amother-of-pearl effect.

[0091] The invention shall now be explained in further detail withreferences to the drawings.

[0092]FIGS. 1, 2, 3, 4 and 5 are cross-sections representing fourdifferent structures of the laminate of the invention, comprising theminifluted ply A, or plies A and D, and the straight ply B or plies Band C. The flutes in each of these structures can extend longitudinallyor transversely, seen in relation to the machine direction of theflute-forming and laminating machinery.

[0093]FIG. 6 is an enlarged detail of FIG. 1 to illustrate how theseplies themselves can be laminates of films, and how these films can bemultilayered as made by co-extrusion, this being done to facilitatebonding and lamination.

[0094]FIG. 7 is a principal sketch representing the steps from formationof the miniflutes in A to lamination of A with B in the manufacture ofthe product shown in FIG. 2, the different steps being represented bythe cross-sections of the films A and B and by the cross-sectionsthrough the axis of the rollers of the surfaces of the rollers.

[0095]FIG. 8 is a sketch of the machine line corresponding to FIG. 7with addition of the means to laminate straight film C to A opposite toB.

[0096]FIGS. 9a, 9 b and 9 c are sketches illustrating the cross-laminateconstructed as stated in claim 22.

[0097]FIGS. 10a, b and c represent sections parallel to the flutes andthrough the middle of a non-bonded zone, showing applications of theinvention in which the channels or pockets formed between ply A and plyB are used as mini-containers or to canalize a flow of air or water,namely in FIG. 10a as mini-containers for a protective agent, in FIG.10b for filtration and in FIG. 10c for weather protection.

[0098]FIG. 11 shows a modification of the lamination station of FIG. 8in which there are added filling devices to fill particulate materialinto the flutes before the lamination, and added sealing equipment toform transverse seals after the lamination, thereby making closedpockets which serve as “mini-containers” for the particulate material.

[0099]FIG. 12 is a flow-sheet showing a process for producing thelaminate with transverse fluting and with “first” and “second”attenuated zones (as these expressions have been defined).

[0100]FIG. 13 shows a detail of a grooved lamination roller forformation of transverse fluting, air jets being used to direct the plyinto the grooves and vacuum being used to retain it there.

[0101] With references to FIGS. 1 to 5 it should be mentioned for thesake of clarity, that the wavelength referred to in the foregoing and inthe claims, is the straight linear distance from x to z. This distanceis preferably 3 mm or lower, and as it appears from the example, theinventor has been able to make it as small as 0.8 mm, which howeverneeds not be the ultimate lower limit obtainable and useful. It is notedthat U.S. Pat. No. 5,441,691 (Dobrin et al.) makes embossed film (notheat-bonded laminates) having a generally circular shape of the bosses,with a spacing from centre to centre which can be still finer than these0.8 mm, however the bosses of this patent are drawn much thinner thanthe main body of the film.

[0102] In FIG. 1 the thickness of ply A is generally the same across theply. In case of transverse fluting this can be achieved by the processshown in FIG. 12 (without preceding formation of attenuated zones)however there is a limit, which is of practical importance, of how finethe wavelength can be, seen in relation to the thickness of ply A.

[0103] In case the flutes are made parallel with the machine direction,for formation of the flutes and the lamination is preferably carried outgenerally as shown in FIG. 8. This means there will always be atransverse stretching between intermeshing grooved rollers, and thedegree of fluting will correspond to the degree of stretching. When filmis stretched between very fine grooved rollers, there will be a strongtendency to localize the stretching entirely or predominately on andnear to the tips of the grooves. This can be avoided, but withdifficulty, by using film which in a preceding process has beentransversely stretched, and feeding the film unto the roller at atemperature which is higher than the temperature of the roller.

[0104] However, in the laminate structures shown in FIGS. 2 to 5 thedifferences of thickness resulting from grooved roller stretching hasbeen utilized in a way which generally is an advantage for theproperties of the product. By the exact registration between the groovedrollers for stretching, the grooved roller for lamination and a groovedtransfer roller therebetween, it is arranged that each bonding zonemainly falls within an attenuated zone. As it appears from FIG. 3 therecan be two sets of attenuated zones for each zone of bonding, namely aseries (6) of wider ones (“the first attenuated zones”) within which thebonding zones fall, and a set of shorter ones (101), the latter referredto as the “second attenuated zones”.

[0105] By attenuating ply A at the basis where it is bonded to ply B,the thickness of A is minimized at the location where its contributionto stiffness in the stiff direction in any case is insignificant. Byintroducing the narrow “second attenuated zones” which act as “hinges”,the cross-section becomes almost triangular as shown in FIG. 3. Thismeans that the stiffness is further improved. These attenuated zonesalso introduce a tendency in the material to stretch rather than ruptureunder impact actions.

[0106] To clarify the concepts, each first attenuated zone (6) is perdefinition delimited by the locations (102) where the thickness of ply A(or ply D) as indicated by arrows is the average between the smallestthickness in this zone and the highest thickness in the adjacentnon-bonded zone.

[0107] Structures with “first attenuated zones” as shown in FIGS. 2 to 5and structures with both “first and second attenuated zones”, as shownin FIGS. 3 can also be produced with machinery which make transversefluting. This shall be described later.

[0108] In FIG. 6 both plies A and B are in themselves laminates, forinstance cross-laminates as in claim 22, and each film from which theplies are produced is co-extruded. Therefore A and B are each formed bya lamination process (the “pre-lamination”) prior to the lamination of Ato B. Layer (1) is the main layer in each of the two coex films whichmake A, and layer (2) is the main layer in the two coex films which makeB. Layers (1) and (2) can e.g. consist of high density polyethylene(preferably HMWHDPE) or iso- or syndio-tactic polypropylene (PP) ofblends of one of these polymers with a more flexible polymer, forinstance, for HMWHDPE, LLDPE. If stiffness is the most preferredproperty of the minifluted laminate, plain HMWHDPE or plain PP may bechosen, but if tear and puncture properties play a more important roleand/or superior heat-seal properties are essential, the mentioned blendsmay be more suited.

[0109] Layers (3) are coextruded surface layers with the function toimprove the heat-seal properties of the finished, minifluted laminateand/or modify its frictional properties. Layers (4) are co-extrudedsurface layers (“lamination layers”) with the two functions: a) tofacilitate the pre-lamination and b) to control the bonding strong,otherwise the tear propagation strength suffers).

[0110] Similarly, layers (5) are co-extruded surface layers tofacilitate the lamination of the entire A to the entire B and controlthe strength of the bonding between A and B.

[0111] With reference to FIG. 7 and FIG. 8 the structure shown in FIG. 2can be formed by passing film (A) first over the grooved pre-heatingroller (6 a) which heats it only along the lines which shall becomeattenuated, then over the grooved stretching rollers (7) and (8),further over grooved transfer and flute-stabilizing roller (9), andfinally over grooved lamination roller (10) and its rubber-coatedcounter-rollers (11), while film (B) is passed over the smooth rollers(12) and (11). The grooves of all of the rollers are circular so thatthe flutes are formed in the machine direction. If B is transverselyoriented and therefore has a tendency to transverse shrinkage, rollers(12) and (11) are preferably supplied with devices, e.g. belts, to holdthe edges (not shown). All of these rollers are temperature controlledrollers, rollers (9), (10), (11) and (12) being controlled at thelamination temperature, rollers (6 a) and (8) at a somewhat lowertemperature and roller (7) at a temperature about 20 or 30° C. (Therecan be further rollers for preheating of B). By choice of suitable,coextruded surface layers—see (5) in FIG. 6—the lamination temperatureis kept far below the melting range of the main layers in (A) and (B).The temperature of the zones (6) in (A) during the transverse stretchingbetween rollers (7) and (8) is preferably still lower, e.g. in the rangeof about 50-70° C. and the rest of (A) much lower, e.g. around roomtemperature, as it also appears from the mentioned roller temperatures.If the main layers in (A) and (B) consist of plain HDPE or blend of HDPEand LLDPE, the lamination temperature is preferably chosen between about80 and about 110° C., and the coextruded lamination layers, which canconsist of a suitable plain or blended copolymer of ethylene, are chosento produce lamination at this temperature.

[0112] The crests on roller (8) has very small radius of curvature, e.g.about 0.05 mm or an extremely narrow “land”. The crests on roller 6 awhich have the function to preheat, may, depending on the film, besimilar or somewhat rounder or with a slightly wider land. The crests onrollers (7) and (9) have a higher radius of curvature or a wider land,to avoid transverse stretching on these crests. Suitable values for thesizes of the grooves are mentioned below in the example.

[0113] The different temperatures on the different grooved rollers causedifferent thermal expansions, compared to a state where all have roomtemperature, and this must be taken into consideration when the groovedrollers are constructed, since they must fit exactly to each otherduring operation. (10° C. heating of a 10 cm long steel roller segmentcauses about 0.011 mm expansion of this segment). Reference is againmade to values in the example.

[0114] Rollers (7), (8) and (10) are driven, while rollers (6 a), (9),(11) and (12) may be idling.

[0115] As it will be understood, the attenuation of A in the zones (6)takes place almost entirely by the transverse orientation at atemperature essentially below the melting range of the main body of A.This attenuation therefore does not cause any significant weakening ofA's transverse strength, contrarily it will normally cause an increaseof this strength. After the transverse stretching on the crests ofroller (8) the width of the “first attenuated zones” (6) shouldpreferably not exceed (as a rule of the thumb) half the wavelength, butthe degree of stretching should normally be as high as practicallyobtainable, while the degree of transverse stretching between the “firstattenuated zones” normally should be as low as practically obtainable,with the intended result that ply A in the unbonded zones becomes asthick as the chosen square metre weight of A allows and the flutesbecome as high as possible.

[0116] A practical way of achieving that the first attenuated zones andthe zones of bonding match with almost equal width is the following: therelatively flat crests on the laminating roller (10) are made slightlywider than the chosen width of the first attenuated zones, and thetemperature and velocities are adjusted to each other in such a way thatthe first attenuated zones (6) become heated to a temperature at whichthe material will laminate with B, while the thicker A-ply between zones(6) does not reach a temperature at which lamination can take place.

[0117] The use of longitudinally oriented A-ply as in claim 6 willimpart a tendency in A to “neck down” and form thin longitudinal lineswhen A is stretched transversely. Therefore, longitudinally orientedA-ply will enhance the possibilities of getting a sharp distinctionbetween strongly attenuated zones (6) and non-attenuated ply A betweenthese zones.

[0118] Theoretically there will always occur some attenuation also ofthe B-ply in the zones of bonding, since the bonding is establishedunder pressure, but this attenuation has no positive effect and shouldpreferably not exceed 20%. Due to the presence of lamination layers (see(5) in FIG. 6) such attenuation of the B-ply can be made negligible.

[0119] In FIG. 8 the minifluted laminate leaving lamination rollers 10and 11 is marked (B/A), In this figure it proceeds for lamination inconventional manner with the non-waved, mono-/or multilayered film Ccoming from the smooth steel roller (13). The lamination takes placebetween the smooth steel rollers (14) and (15) of which at least roller(14) is heated to a convenient lamination temperature and is driven. Thewaved film A is heated to lamination temperature, at least on its freecrests, by means of hot air from the blower (16). Rollers (14) and (15)are kept at a distance from each other which is small enough to effectthe lamination but big enough to avoid excessive flattening, e.g.between 0.2 and 0.6 mm. When A, B and C are very thin films, e.g. eachin the range of 0.03-0.10 mm thick (for A this refers to the non-wavedform) such conventional lamination would have been very difficult due tothe floppiness of waved A, but since the flutes now have beenconsolidated by the bonding to B, the lamination of A to C presents noparticular difficulty.

[0120] The laminate leaving the lamination rollers (14) and (15) ismarked B/A/C. It is cooled, e.g. by air (not shown) and may normally bereeled up or flip-flopped, since it normally is sufficiently flexiblematerial although fluted, or it may directly be cut into lengths.

[0121] To make the laminate shown in FIG. 5, one option is to make theA/B laminate shown in FIG. 2, and laminate this over the rollers (11)and (10) with the fluted ply D leaving roller (9). This requires exactregistration between the rollers which make the A/B laminate and roller(1)). Alternatively B can consist of e.g. two films B1 and B2. Then intwo mutually independent processes there are made an A/B1 laminate and aD/B2 laminate, and the two are bonded together with B1 against B2 in anextrusion lamination process.

[0122] With certain modification the line shown in FIGS. 7 and 8 canalso be used to make the laminate of FIG. 3, which has “secondattenuated zones”. For this purpose roller (6 a) should have the samesurface profile and the same low temperature as roller (7), and itshould be preceded by and in slight engagement with a roller with thesame surface profile as roller (8), which roller should have the samehigher temperature as roller (8).

[0123] In the minifluted “multi-crosslaminate” shown in FIGS. 9a, 9 band 9 c, the two coextruded films (1 a) and (1 b) from which A is madeby “pre-lamination”, are oriented in criss-crossing directions, whichform an angle lower than 45° with the longitudinal direction (the flutedirection) as symbolized by the arrows (1 aa) and (1 bb). This gives aresultant main orientation direction for A parallel with the flutedirection, symbolized by the arrow marked A′. Similarly the twocoextruded films (2a) and (2b) from which B is made by “pre-lamination”,are oriented in criss-crossing directions, which form an angle higherthan 45° with the flute direction, as symbolized by the arrows (2 aa)and (2 bb). This gives a resultant main orientation direction of Bperpendicular to the flute direction, symbolized by the arrow B′.

[0124] In FIG. 10a, which as mentioned shows a longitudinal sectionthrough a flute in ply A, the latter has been flattened and sealed toply B at intervals (103) to form pockets or “mini-containers”, and thesemini-containers have been filled with a particulate substance (104)which has a purpose for the use of the laminate, e.g. for protection ofmaterial packed or wrapped up in the latter. As one among many optionsit may be an oxygen scavenger. To enhance the action of the substancethe flutes may be supplied with fine perforations on the side towardsthe packed product. The substance may also e.g. be a fire retardantmaterial such as CaCl₂ with crystal water, or just fine sand to increasethe bulk density of the laminate.

[0125]FIG. 11 which shall be described below, shows how the particulatesubstance can be fed into the flutes of ply A prior to its laminationwith ply B, and how the flutes can be closed to pockets by transversesealing after the lamination, without any essential contamination ofthese transverse seals.

[0126] A laminate between a fluted thermoplastic film and a non-flutedthermoplastic film with a filling material between is known fromJapanese Patent publication No. 07-276547 (Hino Masahito). However, inthis case the filling material is a continuous porous sheet (forabsorption) which extends from flute to flute without interruptions, sothat there is no direct bonding between the flute and the non-flutedfilms. One of the thermoplastic films is first directly extruded untothis porous (e.g. fiberformed) sheet, then the two together are given afluted shape between gear rollers while the thermoplastic film still ismolten, and finally a second thermoplastic film is extruded directlyunto this fluted assembly to join with the porous sheet. Hereby thebonding necessarily must be very weak, and the mechanicalcharacteristics must be completely different from those of the presentproduct. The wavelength of the fluting is not indicated.

[0127] In the technical filter material for liquid or gas flows shown inFIG. 10b there is inserted a strand or yarn into each flute—inconnection with the description of FIG. 11 it shall be explained howthat can be done—and both sides of each channel formed by fluted ply Aand non-fluted ply B is supplied with a row of perforations, (106) inply A and (107) in ply B. These rows are mutually displaced as shown sothat the liquid or gas passing from one surface of the laminate to theother, is forced to follow a channel over a distance corresponding tothe displacement. The fitting between the yarn and the channel may beimproved by shrinkage of A and/or B after the lamination process.

[0128] The pocket structure shown in FIG. 10a can also be used forfiltration purposes if ply A and ply B are supplied with mutuallydisplaced holes. Then the particulate substance (104) can e.g. consistof active charcoal, or an ion-exchange resin, or for simple filtrationpurposes fine sand. Also in this case a tightening of the passage bymeans of shrinkage can be advantageous or may even be essential.

[0129] Practical examples of the use of such filter materials are forair filtration systems including absorption of poisonous substances, andion-exchange processes. In both cases the laminate can have the form ofa long web which is slowly advanced transversely to the flow whichpasses through it.

[0130] Another practical use is as a substitute of geotextiles e.g. forroad constructions. Such textiles must allow water to penetrate but holdback even fine particles. The present laminate, e.g. filled with finesand in the pockets, is suitable for this use.

[0131] For such filtration purposes, high puncture strength will oftenbe needed, and the laminate then preferably comprises oriented,cross-laminated films.

[0132] For the filtration purposes the condition that the wavelengthshould not exceed 3 mm, is often less important since appearance andhandle may not be a primary concern as it is in the case of laminatesfor ordinary tarpaulin uses.

[0133] The weather protective laminate shown in FIG. 10c, e.g. forraincoats, also has a pocket structure, whereby ply A is heat-sealed toply B by transverse seals at locations (103), but there is noparticulate substance in the pockets. Like the laminate for filtration,each line of pockets is supplied with perforations in a displacedsystem, here shown as groups of perforations (109) in A and similargroups (110) in B, and these groups are mutually displaced. In thissketch it is considered that ply A is on the side where it rains, and aperson, animal or item, which the laminate shall protect, is on the plyB side. (It could be the other way round). It is also considered thatthe direction shown by arrow (108) is upward. Since the perforations(109) are at the bottom of the pockets, and because of the gravityforce, only the bottom of the pockets may be filled with rainwater,while in principle no water will reach the perforations (110). On theother hand there is free passage of air and transpiration between thehole groups (109) and (110). Also in this product the wavelength may tosome extent exceed 3 mm.

[0134] The modification of the FIG. 8 machine-line, which is shown inFIG. 11, is adapted to fill a particulate substance (104) into thechannels formed between A and B. The filling is here shown veryschematically. The powder (104) is taken from a hopper (111) and isadministered by means of an adjustable vibrator (not shown). It fallsinto the fluted ply A at the upper side of the grooved lamination roller(10). At regular time intervals hopper (111) is filled up with thepowder (104). The means for this are not shown. Other conventionalsystems for administering the powder (104) onto ply A on roller (10) mayof course be chosen.

[0135] Roller (10) vibrates (means not shown) so that the powder ismoved from the higher zones, i.e. those which become bonded zones when Ameets B in the nip between (10) and (11), into the lower zones, whichbecome the “channels”.

[0136] Having left the laminating rollers (10) and (11). The A+B−laminate with powder (104) in the channels moves towards the cog-roller(113)—its surface is shown in a detailed part-drawing—and itsrubber-coated counter-roller (114) which together flatten and close thechannels by making transverse seals. Roller (113) is vibrated in orderto remove powder away from the channel-parts which become flattened andsealed.

[0137] Both rollers (113) and (114) are heated to a temperature neededfor the sealing, and since the laminate while entering these rollersstill is at about a temperature suitable for heat-sealing due to theprevious temperatures, this second heat-seal process needs not cause adeceleration of the entire process.

[0138] Ply A and/or ply B may be perforated by means of pin-rollersafter rollers (10)/(11) and in front or after the pair of rollers(113)/(114). In case mutually displaced rows of perforations are needed(see FIGS. 10b and c) and pin-rollers for ply A and ply B must besuitably coordinated, and in case the perforations should have a fixedrelation to the transverse seals (see FIG. 10c, the pin-rollers must becoordinated with roller (113).

[0139] In order to make the product shown in FIG. 10a, rollers (113) and(114) are omitted or taken out of function, and instead of administeringpowder into ply A, there is at the same place laid a yarn into eachflute. Each yarn is taken from a separate reel.

[0140] At some stage after rollers (10)/(11), ply A and/or play B may besubjected to transverse shrinkage. If this is done with ply A only, itmay be sufficient to heat the ply A-side of the laminate to an adequatetemperature by means of hot air or on one or more hot rollers. If ply Bshould be involved in the shrinkage it may be necessary to hold thelaminate at the edges while it shrinks. This may be done by means of anordinary tenterframe, but the latter should be set up to work.“inversely” so that the width gradually is reduced instead of increased.

[0141] The methods applied for making pockets from the flutes, fillpowder into these flutes, and making suitable perforations, have beenexplained in connection with the longitudinally fluted laminate.Analogous methods can be applied in connection with a transverselyfluted laminate (the general method of making such laminate appears fromFIG. 12), and in that case the closing of the channels to form pocketsmay take place by use of a circularly or helically grooved roller.However, it is not considered practically possible to lay down yarn intransverse flutes at industrially acceptable velocities.

[0142] The process for making the transversely fluted laminate, whichappears from the flow-sheet FIG. 12 is generally analogous to theprocess which is described in connection with FIGS. 7 and 8, and theprofiles of the grooved rollers can also be generally similar, exceptthat for the process of FIG. 12 the grooves extend axially, while forthe process of FIGS. 7 and 8 they are circular.

[0143] Step 1: Ply A is longitudinally stretched in very narrow zoneslocalized on the tips of a hot roller which has a profile similar tothat of roller (8). The grooved counter-roller, which is cold, has aprofile like that of roller (7).

[0144] Step 2: The warm, stretched “second attenuated zones” are cooledon a cold grooved roller which also has a profile like that of roller(7), and then to form “first attenuated zones” between the “second”, plyA is longitudinally stretched between this cold roller and a warmgrooved roller which also has a profile similar to that of roller (8).The stretching is localized to the tips of this roller. Similar to theregistration in printing technology, step 2 is brought in registrationwith step 1 under use of a device which optically detects the stretchedzones.

[0145] Step 3: The flutes are first formed in the grooves of a hotroller with a profile similar to that of roller (10), e.g. under use ofcompressed air, and are held in the grooves e.g. under use of a vacuum,all as explained in connection with FIG. 13, and ply A is then laminatedwith ply B between the crests of this grooved roller and a rubber-coatedcounter-roller, which also is heated. Ply B has been preheated.

[0146] There can be different after treatments as explained in theforegoing.

[0147] In FIG. 13, ply A which has been supplied first with the verynarrow transverse “second attenuated zones” (101), and then with thesomewhat wider, also transverse “first attenuated zones” (6), isdirected into the grooves (115) of the heated lamination roller by meansof compressed air from a row of nozzles of which one (116) is shown. Byuse of registration means, working on basis of optical detection ofzones (6) or (101) it is arranged that the first attenuated zones (6)will cover the crests (118) of the grooved roller. The two sets ofattenuated zones act as hinges so that even a quite heavy ply A may bebent and form the flutes. The latter are held in shape in the groovesunder use of vacuum applied through channels (117) from the interior ofthe roller. Thus ply A is moved in flute shape to the nip (not shown)between the grooved roller and the rubber-coated counter-roller, wherelamination takes place. The vacuum in the grooves is adjusted so thatply A is held firmly when this is needed, but can be released where thatis needed. There can also be a valve arrangement inside the groovedroller to eliminate the vacuum during the release.

EXAMPLE

[0148] A 2-ply laminate of fluted ply A and non-fluted ply B with Alongitudinally and B transversely oriented is manufactured on apilot-unit constructed as shown in FIGS. 7 and 8, but terminating afterthe lamination of A and B have taken place. Both plies consist of onecoextruded, cold-stretched 0.037 mm thick film consisting of HDPE with athin layer on one side, consisting of an ethylene copolymer having amelting range between 95-105° C. This is used as lamination layer in theprocess. The cold-stretching was carried out near room temperature at adraw ratio about 3:1 and was followed by heat stabilization, all byconventional means, and while the film had flat tubular form. The tubewas longitudinally cut to form ply A.

[0149] Processes for continuous manufacture of transversely orientedfilm are well-known and mentioned in the foregoing, but it would havecaused practical complications for the inventor to have such filmmanufactured according to his specifications, and therefore shortlengths of the ply A-film were glued together edge to edge with apressure-sensitive adhesive to form a transversely oriented web.

[0150] All of the grooved rollers have the pitch 1.1000 mm at thetemperature at which they actually are used, but due to the largetemperature differences during the stretching/laminating process, thethermal expansion had to be taken into consideration when these rollerswere machined at 20° C., see the table below. The biggest temperaturedifference between the rollers, as it appears from this table, is 85°,and this corresponds to an expansion of about 0.10 mm per 10 cm rollerlength, while the accumulated error in the fitting between adjacentrollers from end to-end of the rollers must be maintained lower than0.15 mm to obtain the needed registration.

[0151] The table below also indicates the radius of curvature (R) or thelength of a “land” on the crest of each grooved roller, as seen in theaxial section in FIG. 7. Roller No. 6a 7 8 9 10 Crest land R = 0.2 landR = 0.15 Land mm 0.4 0.15 0.7 Temperature 70 20 70 105 105 ° C. Pitch mm1,0993 1,1000 1,0993 1,0988 1,0988

[0152] It is of course not practically possible to achieve such a highaccuracy in the pitch seen individually from groove-to groove, but it isessential that errors in the pitch do not accumulate by more than 0.05mm. This is best achieved when the surface parts are made from segmentsand accumulated errors are eliminated by fine grinding of the segmentends and/or thin shims (foils) are inserted between the segments. In theactual pilot machine the length of the grooved part of each rollersurface was about 450 mm and was assembled from 3 segments. It is judgedthat in an industrial machine the rollers can be made in up to about 5 mlength, but in that case the accuracy from end to end has to be checkedwith laser measurements and adjustments made as explained.

[0153] The transverse stretching, which is the basis for theflute-formation and which forms the “first attenuated zones”—later thezones which become bases, not crests of the flutes in the laminate—takesplace by the intermeshing between rollers (7) and (8) and becomeslocalized to a zone on and nearby the crests of roller (8). This isbecause roller (8) is hot and has a relatively sharp crest, while roller(7) is cold and has a much rounder crest (higher radius of curvature R).It is relevant also in this connection that ply A is uniaxially orientedin the machine direction and therefore has a high tendency to“neck-down” and form sharply delimited attenuated zones when it istransversely stretched.

[0154] The function of roller (6 a) is to preheat the zones which are tobe stretched on the tips of roller (8). In this example the “land” onthe crests of roller (6 a) are wider than the “land” on the crests ofroller (8). This has been chosen in order to counteract the verypronounced tendency in the film to “neck-down”, in other words, to makethe limits of the “first attenuated zones” smoother. In other cases e.g.when ply A has a pronounced transverse orientation and therefore notendency to “necking down” by transverse stretching, the “land” on thecrests of roller (6 a) which preheats the film, should be no wider thanthe “land” on the crests of roller (8).

[0155] Between rollers (6 a) and (7) there is a slight but almost zeroengagement to avoid wrinkles without stretching the films.

[0156] Having left the transverse stretching roller (8), ply A is takenover by transfer roller (9). This is heated in order to help the shapingof flutes in the zones which have not been stretched. At this-stage the“first attenuated zones” are still deeply curved, but when (A) is takenover by the flat 0.4 mm wide crests (lands) on the grooved laminatingroller (10) the “first attenuated zones” are flattened almost over theirentire width except at their boundaries where the thickness graduallyincreases, and by means of the rubber-coated counter-roller, which onits surface has temperature 80° C., this flat portion is laminated tothe transversely oriented ply B.

[0157] Prior to the experimental run the axial position of the groovedrollers are very carefully adjusted to each other, and so is theintermeshing between adjacent grooved rollers. The intermeshing betweenrollers (7) and (8) is set to make the depth of the fluting 0.40 mm, asmeasured in microscope on a cross-section of the finished laminate.

[0158] When leaving the stretching/laminating apparatus, the miniflutedlaminted is aircooled and is reeled up on a core of diameter 250 mm. Inthe test report below this laminate is called “Sample I”.

[0159] It is noted that although the pitch of each grooved roller in theline is 1,1000 mm referring to the temperature at-which the roller hasbeen-operated, the wavelength of the fluting in the final miniflutedlaminate, due to transverse shrinkage, is only 1.0 mm.

[0160] As a principal experiment there is out specimens of this film, 30cm long in the machine direction and 20 cm wide in the transversedirection, and these specimens are subjected to further transverseshrinkage by a primitive arrangement which imitates an “inverse”operation of a tenter frame. The two 30 cm long edges are fixed to twosticks, which are held by hand, and an even shrinkage is arranged bymoving the specimen over a roller surface, which is heated to 115° C.,with the B film contacting the roller. Hereby the wavelength is reducedfrom 1.0 mm to 0.8 mm.

[0161] Sample II, made for comparison: By a relatively primitivearrangement there is made specimens of corrugated board material fromthe same film as used to make “Sample I” (coextruded coldstretchedHDPE-film of thickness 0.037 mm), with all dimensions of sample A,namely as follows: Wavelength Bonded Zones Flute-depth Sample mm mm mm I1.0 0.4 0.4 II 5.5 2.2 2.2

[0162] It is noted that II's wavelength, 6.0 mm, is slightly less thanthe minimum mentioned in patent literature namely in U.S. Pat. No.4,132,581.

[0163] In both samples I and II, the direction of orientation in ply Ais parallel with the flutes, and the direction of orientation in B isperpendicular to the flutes.

[0164] Sample B is manufactured with a small laboratory machineconstructed as explained in connection with FIG. 13, but in this casethere has-now been any need to make “first attenuated zones” and “secondattenuated zones”. The flutes become perpendicular to the machinedirection. Like the grooved laminating roller (10) used in themanufacture of sample I, this grooved laminating roller is heated to105° C.

[0165] Sample III, made for comparison: The same film (coextrudedoriented HDPE, 0.037 mm thick) is crosslaminated with itself without anyfluting being made.

[0166] Comparisons Between Samples I, II and III:

[0167] Appearance and Handle:

[0168] (II) looks and feels like a board material, but is instable whenbent or compressed between the fingers.

[0169] (I) has a rather textilis look, can stand a substantial amount ofbending and compression between the fingers without changing itscharacter, and it has a feel of “bulk”.

[0170] Bending Tests:

[0171] (I) and (II) are bent over cylindrical bodies of differentdiameters, and it is examined how small that diameter can be before theflutes begin to collapse in a non-elastic manner, i.e. so that thereremain marks in the flutes after the specimen has been straightened outagain.

[0172] (II) can withstand bending down to a diameter of 250 mm, while(I) can withstand bending down to a diameter of 50 mm.

[0173] Stiffness Measurements:

[0174] 10 cm long specimens are cut out from samples (I), (II) and(III).

[0175] The specimens from sample (I) each comprises 20 flutes and at theedges a bonded zone. The width of these specimens is 21 mm.

[0176] The specimens from sample (II) each comprise 4 flutes and at theedges a bonded zone. The width of these specimens is 23 mm.

[0177] The width of each sample (III) specimen is 21 mm.

[0178] For controlled bending of the specimens there is made a verylightweight support arrangement comprising two supports with 50 mmspacing between. This support arrangement is placed on the table of aletter balance. The bending is effected by means of a cylinder which hasa diameter 50 mm and starts pressing at the middle of the supportedsample. This cylinder is assembled on a stand and can be moved up anddown. Corresponding values of the depression in mm and the resistingforce in grams are measured and plotted. Up to a certain limit there isa linear dependence, and from the declination of the line and stiffnessis calculated as grams force per mm depression.

[0179] In order to obtain reliable reading for sample (III), 10specimens are laid one on top of the other. The value of stiffness isdetermined for this bunch and divided by 10.

[0180] Results

[0181] Surprisingly samples (I) and (II) show the same stiffness, namely1.6 gram per mm, while sample (III) shows 0.13 gram per mm, in otherwords the present invention has magnified the stiffness in one directionby a factor of about 12, as measured by this method.

[0182] It should have been expected that sample (III) would have shownhigher stiffness than sample (I). When this is not the case, theexplanation probably is that the flutes may have been pressed relativelyflat right from the beginning of the depression, although in elasticmanner.

[0183] In the characterisation of the product and method of theinvention, it has been emphasised that the wavelength of the fluted plyA or the pitch on the grooved laminating roller should be no more that 3mm in order to give the corrugated laminate the character of a flexiblefilm rather than a board material. However, in connection with thedescription of the filter material, in which liquid or gas passes fromholes in one ply to displaced holes in the other ply, and on the waypasses a filler, it was nevertheless stated that for such purposes thewavelength may exceed the 3 mm. Similar is true for the describedweather protective corrugated laminate, in which there also aredisplaced holes, but usually no filler, and the gravity force is used to“filter” the rainwater from the passing air.

[0184] Furthermore, the making of “first attenuated zones” andoptionally also “second attenuated zones” has been explained as usefulmeasures for obtaining the “miniflutes”, be it in connection withlongitudinally or transversely fluted laminates. Since these zones actas “hinges”—see e.g. FIG. 13—they enable for a given thickness of ply Aa finer wavelength and/or deeper fluting then it otherwise could beachieved. In the foregoing there has also been stated other usefuleffects of the “fist attenuated zones” and the “second attenuatedzones”, and it is clear that similar advantages can be achieved when thewavelength of the product or the pitch of the grooved lamination rollerexceeds 3 mm.

[0185] Therefore the product and the making of the “first attenuatedzones” and optionally and “second attenuated zones” placed as it hasbeen described in the foregoing, is considered an inventionindependently of the wavelength.

1. Laminate comprising at least a monofilm formed or multifilm formedply (A) and another monofilm formed or multifilm formed ply (B) bothmainly consisting of thermoplastic polymer material, whereby at least Aconsists of cold-orientable material in which A has a waved fluteconfiguration while B is not waved, and B on a first side is adhesivelybonded in bonding zones to the crests on a first side of A,characterised in that the wavelength (A) of the said configuration is nomore than 3 mm, that the adhesive bonding has been established through alamination layer, and in that either the thickness of A is generally thesame within the non-bonded zones as it is within the bonded zones, or Aexhibits first solid-state-attenuated zones extending parallel to theflute direction, each bonding zone mainly being located within a saidfirst attenuated zone whereby each said first attenuated zone isunderstood as delimited by the positions where the thickness is anaverage between A's lowest thickness within the first attenuated zoneand A's widest thickness within the adjacent non-bonded zone. 2.Laminate according to claim 1, characterised in that the ply A by thechoice of polymer material or by an incorporated filler or byorientation, within the non-bonded zones exhibits an average yieldtension parallel to the direction of fluting, which at an extensionvelocity of 500% min⁻¹, is no less than 30 Nmm⁻², preferably no lessthan 50 Nmm⁻³ and still more preferably no less than 75 Nmm⁻². 3.Laminate according to claim 1 or claim 2 characterised in that thewavelength of each flute including an adjacent bonding zone is no longerthan 50 times the highest thickness of A within the flute, preferably nomore than 40 times and still more preferably no more than 30 times thesaid thickness.
 4. Laminate according to any preceding claimscharacterised in that the width of each bonding zone is no less than 15%preferably no less than 20% and still more preferably no less than 30%of the wavelength.
 5. Laminate according to any of the preceding claimscharacterised in that the width of the non-bonded zone of A as measuredbetween the two adjacent bonding zones and measured along its curvedsurfaces is no less than 10% and preferably no less than 20% longer thanthe corresponding linear distance.
 6. Laminate according to any of thepreceding claims characterised in that A, within each non-bonded zoneand outside the first attenuated zone if such zone is present, ismolecularly oriented mainly in a direction parallel to the direction ofthe flutes or in a direction close to the latter as determined byshrinkage tests.
 7. Laminate according to claim 6, characterised in thatB also is molecularly oriented and B's orientation within eachnon-bonded zone in a direction perpendicular to the direction of theflutes is higher than A's average orientation in the same directionwithin the non-bonded zone, the said two orientations being determinedby shrinkage tests.
 8. Laminate according to claims 6 or 7,characterised in that the yield tension in A in a direction parallelwith the flutes and the yield tension in B in a direction perpendicularto the flutes, both referring to the cross-section of the respective plyand determined in the non-bonded zones on narrow strips at an extensionvelocity of 500% min⁻¹, is no less than 30 Nmm⁻², preferably no lessthan 50 Nmm⁻² and still more preferably no less that 75 Nmm⁻². 9.Laminate according to any of the preceding claims, characterised in thatB has a lower coefficient of elasticity than A, both as measured in thedirection perpendicular to the flute direction.
 10. Laminate accordingto claim 7, characterised in that the choice of B and of depth offluting is so that by stretching of the laminate perpendicular to thedirection of the fluting up to the point where the waving hasdisappeared, B still has not undergone any significant plasticdeformation, preferably B is selected as a thermoplastic elastomer. 11.Laminate according to any of the preceding claims, characterised in thatit comprises at least two films which each has a main direction oforientation and which are laminated so that the said two directionscross each other.
 12. Laminate according to any of the preceding claims,in which said first attenuated zones are present in A characterised inthat each such zone of attenuated A, if it extends beyond thecorresponding zone of bonding into a non-bonded zone of A, is limited toa width which leaves more than half of and preferably no less than 70%of the width of the non-bonded zone, as not belonging to any firstattenuated zone, this width being measured along the curved surfaces.13. Laminate according to claim 12, characterised by a secondsolid-state-attenuated zone (hereinafter the second attenuated zone)between each pair of adjacent first attenuated zones said secondattenuated zones being narrower than said first attenuated zones andlocated on the crests of A.
 14. Laminate according to any of thepreceding claims, characterised in that the wavelength of A is no morethan 2.5 mm, preferably no more than 2 mm and more preferably no morethan 1.5 mm.
 15. Laminate according to any of the preceding claims,characterised in that it comprises a further non-waved monofilm formedor multifilm formed ply (C) of thermoplastic polymer material, C beingbonded to the crests of A on the second side of the latter through alamination layer.
 16. Laminate according to any of the preceding claimscharacterised in that it comprises a further monofilm formed ormultifilm formed ply (D) consisting of thermoplastic, cold-orientablepolymer material, said ply having waved flute configuration, the crestson one side of D being bonded to the second side of B through alamination layer, and the wavelength of D's flute configurationpreferably being no more than 3 mm.
 17. Laminated according to any ofthe preceding claims, characterised in that at least some of the flutesare flattened at intervals and preferably bonded across each ones entirewidth at the flattened locations to make the flute form a row of narrowclosed elongated pockets.
 18. Laminate accordingly to claim 17,characterised in that the flattened portions of a number of mutuallyadjacent flutes or of all flutes form a series of lines transverse tothe longitudinal direction of the flutes.
 19. Laminate according to anyof the preceding claims, characterised in that the bonding of the crestson A, is effected through selected surface layers formed in aco-extrusion process.
 20. Laminate according to any of the precedingclaims, characterised in that the mono- or multifilm formed plies mainlyconsist of polyolefin.
 21. Laminate according to claim 12, characterisedin that said first attenuated zones of A are attenuated so that theminimum thickness in that zone is less than 75% of the maximum thicknessof A in the non-bonded zone, preferably less than 50% and morepreferably less than 30% of that maximum thickness.
 22. Laminateaccording to any of the preceding claims, characterised in that A and Beach has a main direction of orientation, either by being uniaxiallyoriented or unbalanced biaxially oriented, or by in itself being across.-laminate of uniaxially oriented or unbalanced biaxially orientedfilms, such cross-laminate exhibiting a resultant main direction oforientation, whereby the resultant main direction of orientation in A isgenerally parallel with the longitudinal direction of the flutes, whilethe resultant main direction of orientation in B forms an angle to thesaid direction in A.
 23. Laminate according to claim 15, characterisedin that B and C each has a main direction of orientation, either bybeing uniaxially oriented or unbalanced biaxially oriented, or each initself being a cross-laminate of uniaxially or unbalanced biaxiallyoriented films, said cross-laminate exhibiting a resultant maindirection of orientation whereby the main direction of orientation in Bcriss-crosses the main direction of orientation in C.
 24. Laminateaccording to claim 23, characterised in that A in a non-oriented stateexhibits a co-efficient of elasticity E which is lower than E of both Band C in non-oriented state, preferably by a factor of at least 1.5 andmore preferably at least
 2. 25. Laminate according to claim 24,characterised in that the flutes are flattened at intervals and bondedacross each ones entire width to make the flute form a row of narrowclosed pockets.
 26. Laminate according to any of claims 1 to 22characterised in that by the choice of polymer material or by anincorporated filler or by orientation, the co-efficient of elasticity Ein Ply A measured in the unbonded zone in the direction parallel to theflute as an average over the unbonded zone is no less than 700 MPa, andpreferably no less that 1000 MPa.
 27. Laminate according to any of thepreceding claims, characterised in that at least some of the channelsformed by the flutes and the matching non-waved film material, whichchannels may be closed to pockets, contain a filling material inparticulate, fibrous, filament or liquid form.
 28. Laminate according toclaim 27, characterised in that said material is a preservative forgoods intended to become packed in or protected by the laminate,preferably an oxygen scavenger or ethylene scavenger, a biocide, such asa fungicide or bactericide, a corrosion inhibitor or a fireextinguishing agent, optionally with perforations established in theflutes or non-waved film material to enhance the effect of saidpreservative.
 29. Laminate according to claim 27, characterised in thatsaid filling material consists of reinforcement yarn or reinforcementfilaments.
 30. Laminate according to claim 27, characterised in thatsaid filling material is adapted to act as a filter material by holdingback suspended particles from a liquid passing through the channels orpockets or is an absorbent or ion exchanger capable of absorbing orexchanging matter dissolved in such liquid, said filler optionally beingfibre-formed or yarn-formed, and that each filled flute and matchingnon-waved film material is supplied with a row of perforations, wherebythe perforations or groups of perforations in a flute and theperforations or groups of perforations in the matching non-waved filmmaterial are mutually displaced so as to force the liquid with thesuspended particles, while passing from one surface of the laminatetowards the other surface, to run through the filter material in adirection parallel to the longitudinal directions of the flutes.
 31. Abag made from the laminate according to claim 1, characterised in thatthe laminate comprises only the two mono- or multifilm formed plies Aand B, and in that the bottom and top of the bag are generallyperpendicular to the longitudinal direction of the flutes.
 32. Aself-standing bag or pouch made from the laminate according to claim 1,in which the bottom of the bag or pouch is gusseted, and front and backfaces of the bag or pouch are adhesively joined at their edgespreferably by heat-sealing, characterised in that the laminate comprisesonly the two mono- or multifilm formed plies A and B, and in that thebottom and top of the bag or pouch are generally parallel with thelongitudinal direction of the flutes.
 33. A self-standing bag or pouchaccording to claim 32, characterised in that the capability of the bagor pouch to stand on its own is enhanced by flat-pressed lines generallyperpendicular to the longitudinal direction of the flutes. 34.Geotextile substitute capable of letting water through but withholdingthe soil, constructed according to claim 30 and preferably comprisingoriented and cross-laminated films.
 35. Geotextile substituteaccordingly to claim 34, characterised in that the filler is sand. 36.Method of manufacturing a laminate or monofilm formed or multifilmformed ply (A) with another monofilim formed or multifilm formed ply (B)both consisting of thermoplastic polymer material in which A has a wavedflute configuration while B is not waved, and B on a first side isadhesively bonded in zones to the crests on a first side of A, in whichfurther the waved flute structure is formed by the use of a groovedroller, and the said bonding with B is carried out under heat andpressure and also under use of a grooved roller, and at least A isselected as mainly consisting of solid-state orientable material,characterised in that the division on the grooved roller which producesthe lamination on the said crests is at the highest 3 mm.
 37. Methodaccording to claim 36, characterised in that prior to the said bondingprocess A is solid-state stretched in narrow zones to form firstattenuated zones which are parallel to the selected direction offluting, said stretching being generally perpendicular to the saiddirection and carried out between a set of grooved rollers bothdifferent from the grooved roller for lamination, and that the groovedroller for lamination is coordinated with the said set of grooved rollerfor stretching in such a way that each zone of bonding mainly becomeslocated within a first attenuated zone.
 38. Method according to claim37, characterised in that prior to or after the formation of the firstattenuated zones another set of grooved rollers produces secondattenuated zones which is another series of solid-state oriented narrowzones in A, parallel with the first attenuated zones and narrower thanthe latter, and the grooved rollers which produce said second attenuatedzone are coordinated with the grooved rollers which produce the firstattenuated zones so that there is produced a second attenuated zonegenerally in the middle between each two neighbours of second attenuatedzones.
 39. A method according to any of claims 36 to 38, characterisedin that the division of the grooved roller which produces the laminationon the crests is at the highest 2.5 mm, preferably no more than 2.0 mmand still more preferably no more than 1.5 mm.
 40. A method according toany of claims 36 to 39, characterised in that prior to the forming ofthe waved flute structure and if the methods of claims 37 and/or 38 areused, also prior to the formation of the attenuated zones, the film orfilms which constitute A are supplied with orientation in one or bothdirections, the resultant main direction of orientation being in thedirection which is selected to become the direction of fluting. 41.Method according to any of claims 36 to 40, characterised in thatsimultaneously with or subsequent to the bonding of B to A a furthernon-waved monofilm formed or multifilm formed ply (C) of thermoplasticpolymer materials is adhesively bonded to the crests of A on the secondside of the latter.
 42. Method according to any of claims 36 to 40,characterised in that in a manner similar to the forming and applicationof A there is produced a second monofilm formed or multifilm forms ply(D) having waved flute configuration with a wavelength preferably of nomore than 3 mm, and the crests on one side of D are laminated to thesecond side of B simultaneously with or following the lamination of Bwith A.
 43. Method according to any of the claims 36-42, characterisedin that the mono- or multi-film formed plies, mainly consist ofpolyolefin, and are produced by a process involving extrusion. 44.Method according to any of claims 36 to 43 characterised in that thefilms constituting the plies are made by co-extrusion in which there areco-extruded surface layers to enable the lamination without any meltingof the main body of the films.
 45. Method according to any of claims 36to 44 characterised in that after the said lamination at least some ofthe flutes are flattened in locations placed at intervals, preferablyunder heat and pressure sufficient to bond all films in the laminate toeach other in said locations so that the flutes with adjacent filmmaterial form fine elongated pockets.
 46. Method according to claim 45,characterised in that said flattening is carried out with bars or cogswhich have their longitudinal direction arranged transversely to theflute direction and each covering a number of flutes, optionally theentire width of the laminate.
 47. Method according to any of claims 37to 46 characterised in that a suitably distinct stripe formation of thefirst attenuated zones is established at least in part by giving thecrests on the grooved stretching roller intended to produce the stripesa temperature which is higher than the temperature of the crests on theother grooved stretching roller and/or by giving the crests on thegrooved stretching roller intended to produce the stripes a radius ofcurvature which is smaller than the radius of curvature of the crests onthe matching grooved stretching roller.
 48. Method according to any ofclaims 36 to 47 characterised in that particulate, liquid orthread/yarn-formed material is filled into some at least of those flutesin A which, by the lamination to B, are closed to form channels, thisfilling taking place before, prior to or during said lamination. 49.Method according to claim 48, characterised in that after filling thefilled channels are closed at intervals by pressure and heat to formfilled pockets.
 50. Method according to any of claims 48 to 49,characterised in that prior to, simultaneously with or following thefilling step perforations are made in the laminate at least on one sideto help the filling material or part thereof dissipate into thesurroundings or to allow air or liquid to pass through the pack offilling material.
 51. Method according to claim 50, characterised inthat there is made a row of micro perforations on each side of eachfilled channel, said rows being mutually displaced to force air orliquid which passes through the laminate to run a distance along achannel or pocket.
 52. Method according to any of claims 36 to 51,characterised in that B prior to the lamination is supplied withorientation generally perpendicular to the direction which becomesdirection of fluting, and after the lamination B is subjected toshrinkage in a direction generally perpendicular to the direction offluting.
 53. Method according to any of claims 36 to 52, characterisedin that the waved flute structure is established essentially in A'slongitudinal direction under a generally transverse orientation processby taking A through a set of driven mutually intermeshing groovedrollers, the grooves on the rollers being circular or helical andforming an angle of at least 60° with the roller axis.
 54. Methodaccording to claim 53, characterised in that A is passed directly fromits exit from one of the grooved stretching rollers which form thewaving on A to the grooved lamination roller, these two grooved rollersbeing in close proximity to each other and having the same pitch whenmeasured at each ones operational temperature and being mutuallyadjusted in the axial direction.
 55. Method according to claim 53,characterised in that A is passed from its exit from one of the groovedstretching rollers which form the waving on A to the grooved laminationroller over one or a series of heated, grooved transfer rollers, thegrooved rollers in the row starting with the grooved stretching rollersand ending with the grooved lamination roller each being in closeproximity to its neighbour or neighbours, whereby each of the groovedrollers in the row has the same pitch when measured at their respectiveoperational temperature, and being mutually adjusted in-the axialdirection.
 56. Method according to any of claims 36 to 52 characterisedin that each grooved roller used to form the flutes in A and A to B, andeach grooved roller used to form the first attenuated zones according toclaim 37 if such zones are produced, and each grooved roller used toform the second attenuated zones according to claim 38 if such zones areformed, is a grooved roller in which the grooves are essentiallyparallel with the roller axis, and means are provided to hold the flutesof A in the grooves in the roller on which these flutes are formed andbonded during the passage from the position where the flutes are formedto the position where A is bonded to B, said holding means adapted toavoid a frictional rubbing on A during said passage.
 57. Methodaccording to claim 56, characterised in that the flutes in A are formedby use of an air jet or a transverse row of airjets which directs A intothe grooves on the forming roller.
 58. Method according to claims 56 or57, characterised in that if first attenuated zones are formedaccordingly to claim 37 by grooved rollers acting in coordination withthe grooved roller used for lamination, said coordination consists in anautomatic fine regulation of the relative velocities between therollers.
 59. Method according to claim 58, characterised in that whensecond attenuated zones are formed according to claim 38 by groovedrollers acting in coordination with the grooved rollers used to producethe first attenuated zones, said coordination consists in an automaticfine regulation of the relative velocities between the rollers. 60.Method according to claim 36, characterised in that the bonding isestablished through a lamination layer.
 61. Laminate according to claim22, characterised in that there is only the two mono- or multilayeredfilms A and B and A is unoriented states exhibits a co-efficient ofelasticity E which is lower than the E exhibited by B in unorientedstate, preferably by a factor of at least 1.5 and more preferably by afactor of at least
 2. 62. A laminate according to any of the claims 1-26made to be weather (rain and wind) resistant and air-permeable,characterised in that at least some of the channels formed either bywaved ply A and non-waved ply B and/or C and/or waved ply D areconnected to the environment on both sides of the laminate throughperforations, the perforations on the two sides of a channel beingmutually displaced so as to force air or water which pass through thelaminate to run a distance through a channel.
 63. Laminate according toany of the preceding product claims, characterised in that there isprint on A and/or B in the non-bonded zones, the bonded zones beinggenerally devoid of such print.
 64. Method according to any of thepreceding method claims, characterised in that A and/or B is printed onthe surface to become the inside of the laminate, the printing processbeing in register with the flute-forming and lamination processes so asto limit the print generally to the non-bonded zones.
 65. Apparatus forforming a laminate comprising feeding means for feeding a continuous webof ply B formed of a thermoplastic material from a supply to alaminating station; a grooved fluting roller for imposing a waved flutedstructure on a ply of thermoplastic material; feeding means for feedinga continues web of ply A formed of a thermoplastic material from asupply to the grooved fluting roller and thereafter to the laminatingstation in face to face relationship with ply B; wherein the laminatingstation comprises a grooved laminating roller which is capable ofapplying heat and pressure between the crests of the flutes of ply A andply B so as to bond the contacting surfaces of ply A and ply B inbonding zones to form a laminate product; characterised in that thedivision between the crests of the laminating roller is no more than 3mm.
 66. Apparatus according to claim 65 comprising a pair ofintermeshing grooved stretching rollers for solid-state stretching ofply A in a direction substantially perpendicular to the flutes upstreamof the laminating roller, to form first attenuated lines mutuallyseparated in said perpendicular direction, the grooves of the stretchingrollers being adapted and aligned with those of the laminating roller sothat each bonding zone is located mainly within a first attenuated zone.67. Apparatus according to claim 66 in which the apparatus comprisesheating means for heating ply A in discrete zones destined forstretching to form the first attenuated zones, said means preferablycomprising a heated grooved roller positioned so as to allow contact ofthe heated tips of the grooves with ply A upstream of the pair ofgrooved stretching rollers, in line with the grooves of the stretchingrollers.
 68. Apparatus according to claim 66 or 67, in which the radiusof curvature of the tips of the grooves of at least one of thestretching rollers, any heating means, the speed of transport of ply Aand the extent of intermeshing of the rollers are adapted so as toattenuate the thickness of ply A in the attenuated zones to a thicknessthat is less than 75% of the original thickness of ply A, preferablyless than 50%. of the original thickness and more preferably less than30% of the original thickness.
 69. Apparatus according to any of claims66 to 68 in which the radius of curvature of the tips of the grooves ofat least one of the stretching rollers, any heating means, the speed oftransport of ply A and the extent of intermeshing of the rollers areadapted so as to provide an attenuated zone which extends beyond thebonded zone for no more than x % of the linear width between adjacentbonded zones. [This is meant to correspond to claim 12)
 70. Apparatusaccording to any of claims 66 to 69 comprising a pair of secondintermeshing grooved stretching rollers for solid-state stretching ofply A in a direction substantially perpendicular to the flutes upstreamof the laminating roller, to form second attenuating zones mutuallyseparated in said perpendicular direction, the grooves of the secondstretching rollers being adapted and aligned relative to the grooves ofthe laminating roller so that the second attenuated zones are locatedbetween the first attenuated zones whereby a second attenuated zone islocated between each adjacent pair of first attenuated zones. 71.Apparatus according to claim 70 in which the pair of second stretchingrollers are separate from the pair of first stretching rollers. 72.Apparatus according to any of claims 66 to 71 in which the flutingrollers comprises the or each grooved stretching roller pair. 73.Apparatus according to any of claims 65 to 72 in which the division λbetween the crests of the laminating roller is no more than 2.5 mm,preferably no more than 2.0 mm, more preferably no more than 1.5 mm. 74.Apparatus according to claim 73 in which the grooves of the laminatingroller have substantially flat crests having a width in the range (0.15to 0.9) λ, preferably in the range (0.2 to 0.8) λ, more preferably (0.3to 0.75) λ.
 75. Apparatus according to any of claims 65 to 74 in whichthe grooved laminating roller applies heat and pressure on the plys A/Bagainst a flat counter-roller, preferably having a rubbery surface. 76.Apparatus according to any of claims 65 to 75 comprising groovedtransfer rollers between the fluting roller(s) and the laminating rollerwhereby ply A remains in contact with the surface of at least onegrooved roller from the upstream fluting roller to the laminatingstation.
 77. Apparatus according to any of claims 65 to 76 in which thegrooves of each grooved roller are circular.
 78. Apparatus according toany of claims 65 to 76 in which the grooves of each grooved roller areparallel to the roller axes.
 79. Apparatus according to any of claims 65to 78 comprising means for supplying the A/B laminate from thelaminating station to a downstream C ply laminating station; means forsupplying a continuous web of substantially smooth ply C formed of athermoplastic material from a supply to the second laminating station soas to be in face to face relationship with the A/B laminate and incontact with A. wherein the second laminating station comprises rollersfor applying pressure between ply C and the A/B laminate to bond A to C.80. Apparatus according to claim 79 comprising means for heating thesurface of A of the A/B laminate and/or the face of C brought intocontact with the A/B laminate prior to or simultaneously withapplication of pressure in the C-ply laminating station.
 81. Apparatusaccording to any of claims 65 to 80 comprising a grooved ply D flutingroller for imposing a waved fluted structure on a ply D of thermoplasticmaterials; feeding means for feeding a continuous web of ply D formed ofthermoplastic material from a supply to the grooved ply D fluting rollerand thereafter to a ply D laminating station; means for supplying ply Bto the ply D laminating station for face to face contact of ply D withply B on the side of B opposite to the side in face to face contact withA, wherein the ply D laminating station comprises a grooved ply Dlaminating roller for applying heat and pressure between ply D and thecrests of ply D in ply D bonding zones so as to bond the contactingsurfaces in the said ply D bonding zones.
 82. Apparatus according toclaim 81 wherein the division between the grooves of the ply Dlaminating roller λ_(D) is the same as λ and the ply D bonding zones aredirectly opposite the bonding zones of A and B.
 83. Apparatus accordingto any of claims 65 to 82 comprising a printing station for printing anink onto a surface of ply A and/or ply B, preferably in register withthe fluting and laminating rollers, preferably onto a surface of a plydestined to be an internal surface in the laminate product. 84.Apparatus according to any of claims 65 to 83 comprising a fluteflattening station for imposing pressure on the laminate of A and B atintermittent positions along at least one flute, preferably forproviding a continuous flattened zone transverse to the direction of theflutes across the entire width of the laminate in which the contactingfaces of the plies are adhered to one another to form closed pockets.85. Apparatus according to any of claims 65 to 84 comprising a bagforming station for forming bags or pouches from the laminate product byheat sealing side and/or bottom and/or top seals of face to facearranged laminates.
 86. Apparatus according to 85 in which the bagforming station forms gusseted bags with gusseted bottoms andheat-sealed sides, and in which the bottoms are parallel with theflutes.
 87. Apparatus according to any of claims 65 to 84 comprisingperforating means for perforating ply A and/or ply B of the laminatedownstream of the said laminating station, the perforating means beingaligned with the laminating roller whereby the plys are perforatedbetween the bonded zones.
 88. Apparatus according to any of claims 65 to87 comprising a filler station between the fluting roller(s) and thelaminating roller for introducing filling material into the flutesbetween ply A and ply B.
 89. Apparatus according to claim 88 in whichthe filler material is in particulate, fibrous or yarn form.